Thermoelectric and structural properties of a new Chevrel phase: Ti0.3Mo5RuSe8

The new Chevrel phase Ti0.3Mo5RuSe8 has been synthesized and characterized by quantitative microprobe analysis, powder X-ray diffraction, and high-temperature thermoelectric properties measurements. The thermoelectric properties of this compound are compared to the previously reported data for other related Chevrel phases. We report also the results of Rietveld analysis of powder X-ray diffraction data for Ti0.3Mo5RuSe8. This compound adopts the rhombohedral Chevrel phase structure (space group R3¯, Z=3) with hexagonal lattice constants a=9.75430(25) Å and c=10.79064(40) Å. The low level of incorporation and low scattering power of Ti precluded the identification of the Ti positions, and Rietveld refinement was carried out only for the Mo5RuSe8 framework of Ti0.3Mo5RuSe8 (Rp=10.5%, Rwp=14.6%). Rietveld analysis was also used to refine the structure of the unfilled phase Mo5RuSe8 (R3¯, Z=3, a=9.63994(8) Å, c=10.97191(11) Å, Rp=8.0%, Rwp=10.5%). Comparisons between the two structures are made.

A combination of Ti-filling and Ru-substitution in Chevrel phase selenides has been investigated. The compound Ti0.3Mo5RuSe8 was synthesized, and its electrical resistivity (ρ) and Seebeck coefficient (S) were measured up to 1200 K. Comparison of the thermoelectric power factor (PF=S2/ρ) shows that this material performs better than both the Ti-filled phase Ti0.9Mo6Se8 and the fully Ru-substituted phase Mo4Ru2Se8.Figure optionsDownload as PowerPoint slide